1. Field of the Invention
The present invention relates generally to valves for modules of semiconductor processing equipment, and more particularly to a unitary slot valve actuator with dual slot valves and methods of implementing such valves between separate chambers of semiconductor processing equipment so that operations may continue in one chamber during servicing of the other chamber, which semiconductor equipment may be a multi-chamber vacuum system.
2. Description of the Related Art
In vacuum processing of thin film materials, such as in the manufacture of semiconductor devices, multiple process chambers are interfaced to permit transfer of wafers, for example, between the interfaced chambers. Such transfer is via transport modules that move the wafers, for example, through slots or ports that are provided in the adjacent walls of the interfaced chambers. For example, transport modules are generally used in conjunction with a variety of substrate processing modules, which may include semiconductor etching systems, material deposition systems, and flat panel display etching systems. Due to the growing demands for cleanliness and high processing precision, there has been a growing need to reduce the amount of human interaction during and between processing steps. This need has been partially met with the implementation of transport modules which operate as an intermediate handling apparatus (typically maintained at a reduced pressure, e.g., vacuum conditions). By way of example, a transport module may be physically located between one or more clean room storage facilities where substrates are stored, and multiple substrate processing modules where the substrates are actually processed, e.g., etched or have deposition performed thereon. In this manner, when a substrate is required for processing, a robot arm located within the transport module may be employed to retrieve a selected substrate from storage and place it into one of the multiple processing modules.
As is well known to those skilled in the art, the arrangement of transport modules to “transport” substrates among multiple storage facilities and processing modules is frequently referred to as a “cluster tool architecture” system. FIG. 1 depicts a typical semiconductor process cluster tool architecture 100 illustrating the various chambers that interface with a transport module 106. Transport module 106 is shown coupled to three processing modules 108a–108c which may be individually optimized to perform various fabrication processes. By way of example, processing modules 108a–108c may be implemented to perform transformer coupled plasma (TCP) substrate etching, layer depositions, and/or sputtering.
Connected to transport module 106 is a load lock 104 that may be implemented to introduce substrates into transport module 106. Load lock 104 may be coupled to a clean room 102 where substrates are stored. In addition to being a retrieving and serving mechanism, load lock 104 also serves as a pressure-varying interface between transport module 106 and clean room 102. Therefore, transport module 106 may be kept at a constant pressure (e.g., vacuum), while clean room 102 is kept at atmospheric pressure. To prevent leaks between modules during pressure varying transitions, or to seal off a processing module from transport module 106 during processing, various types of gate drive valves are used to isolate the various modules.
For more information on gate drive valves, reference may be made to U.S. Pat. No. 4,721,282, which is hereby incorporated by reference. Another such gate drive valve is shown in U.S. Pat. No. 5,667,197, in which a prior art valve housing is shown having two port openings, and only one valve for one of the two port openings. Thus, it is not possible to close the port that does not have an associated valve. Also, the gate plate valve of the '282 Patent is shown for closing a port between abutting transport and process chambers, and no intermediate valve housing is provided. A drive assembly for the gate plate moves the gate plate in one continuous motion in a vertical path and in a rotating arc toward the internal port to effect a seal or closure of the internal port.
U.S. Pat. No. 5,150,882 shows one valve between various chambers of a treatment system, including between a decompression chamber and an etching chamber. Such one valve is driven for engagement and disengagement with a gate aperture by one air cylinder and a toggle arrangement such that stopper plates hit rollers with considerable impact. Initial vertical movement of a fitting plate is changed to horizontal movement by the link that is rotated counterclockwise, such that the gate moves toward the gate aperture. For the '882 Patent to avoid problems of the prior art, the stopper plates are made from a double boride hard alloy. Further, the single motion of the one air cylinder is not stopped, but instead continues its driving operation after the abutment of the stopper plates with the rollers. Thus, in addition to requiring special materials, the '882 Patent does not provide two valves between adjacent processing chambers.
Other valves for cluster tool architecture systems include a separate actuator for each of two valves, which tends to increase the width of a valve actuation housing or, when attempts are made to reduce such width, to restrict the location at which force is applied by the actuators to the valves. Also, such valves require a separate bellows for each of the two separate actuators. Because the cost of such bellows is substantial (e.g., in the range of $800.00 to $1000.00 each, in year 2000 U.S. dollar terms), it is costly to require two bellows. Further, each such separate actuator is generally driven by a separate pneumatic cylinder, which also increases costs when one separate actuator is required for each of the two valves.
In view of the forgoing, what is needed is a valve assembly between adjacent process or transport chambers, wherein operations in one such chamber may continue while servicing, for example, is performed in the other chamber, and wherein the valve assembly has only one common valve actuator for two valves, thus reducing the cost of the assembly by eliminating one bellows and two pneumatic drives.